Income Taxes (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Taxes [Line Items]
Income tax expense (benefit)	$ 183	$ 195	$ 412	$ 469
Income tax (benefit) expense from discontinued operations	(10)	1,200	22	1,300
Cove Point
Income Taxes [Line Items]
Income tax (benefit) expense from discontinued operations		7		31
East Ohio, PSNC and Questar Gas
Income Taxes [Line Items]
Discontinued operations, deferred tax liabilities	$ 825		$ 825
East Ohio, PSNC and Questar Gas | Cove Point
Income Taxes [Line Items]
Income tax expense (benefit)				29
Ownership percentage	50.00%		50.00%
East Ohio, Questar Gas and PSNC Transactions
Income Taxes [Line Items]
Income tax expense (benefit)			$ 52
Discontinued operations, deferred tax liabilities	$ 841		841
Virginia Electric and Power Company
Income Taxes [Line Items]
Income tax expense (benefit)	$ 141	$ 128	386	$ 311
Production tax credit			$ 53